[FS#1159] SLAAC Only function on WAN interface if WAN is bridged

[LEDE Bugs]

The following task is now closed:

FS#1159 - SLAAC Only function on WAN interface if WAN is bridged
User who did this - Mathias Kresin (mkresin)

Reason for closing: Not a bug
Additional comments about closing: Please reopen the ticket if I was wrong and the issue persists.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1159